CMMG Gas Piston Conversion Review

The CMMG gas piston conversion is designed to make ARs run cooler and cleaner. The bolt carrier remains cool, clean and well lubed as you shoot magazine after magazine of 5.56X45, 6.8mm SPC or 5.45X39.5. Fouling and carbon buildup are greatly reduced. You just boresnake your weapon and wipe down the outside when you finish shooting. Reduced operating temperatures increase the life of components. The unit includes a gas block which replaces the factory unit. This has a Picatinny rail to take replacement bolt-on foresights and has a cut off to enable the use of a .22LR blowback adapter. A bayonet lug is incorporated. Recoil with the AR gas piston conversion is reduced leading to faster follow-up shots. The gas block is a ‘straight line’ design which vents gas pressure directly on the operating rod which transmits the energy to a lug on top of the bolt carrier. The bolt carrier is machined from a single billet to avoid the failures that can happen when conversions of direct gas action carriers are employed. The kit to create an AR gas piston upper comes with a piston tube, bolt carrier and handguard retainer cap. The steel piston used in this AR gas piston conversion is hard chromed. The gas block is hardcoat anodized aluminum. The CMMG gas piston conversion carrier does not include a bolt assembly. The carbine unit comes with a reinforced polymer composite handguard but the mid-length unit requires a free float handguard with sufficient clearance (not included). The carbine version fits carbine length gas system ARs with a barrel that is .750″ OD at the gas port whilst the mid length version fits ARs with a mid length gas system and a barrel that is 0.936″at the gas port. This kit is more difficult to fit than the Osprey – some gunsmithing is involved. It is also more difficult to keep clean, but the gas cut off option is useful.